This invention relates to a sewing device, wherein fabrics are transferred by a fabric transfer mechanism along the surface of a machine table from a first position to a second position with a machine sewing portion being interposed therebetween. During the transfer, machine sewing is effected to form seam lines of predetermined lengths on the fabrics as in a piping sewing device or a darts sewing device. More particularly the present invention relates to a sewing device wherein memory means is provided for storing length data of a plurality of seam lines to be stitched on the fabrics and order data for instructing the order of reading out the aforesaid length data. Each time the fabric transfer mechanism returns to the second position or the first position the length data is repeatedly renewed one after another in accordance with the order data, and, during the movement of the fabric transfer mechanism from the first position to the second position, a sewing machine is driven and stopped during a time period suitable for forming the seam lines in accordance with the length data thereof.
Heretofore, there has been developed a piping sewing device filed by the present applicant, in which nine types of pattern numbers and sewing lengths are desirably selected in advance and made it possible to be inputted into a microcomputer. Out of all these pattern numbers, one pattern number is selected to control the sewing machine in its start and stop, so that a seam line having a length corresponding to the pattern number selected can be formed during the movement of the fabric transfer mechanism from the first position to the second position. In using this piping sewing device, either one of the following methods must be selected when the device is applied to a material such as a sack coat, in which a plurality of pipings (pockets) different in length from one another are formed in a body material. Namely, the methods include a first method, in which, in one body material piece, each time one piping is formed, the body material piece is removed from the fabric transfer mechanism, the succeeding body material piece is set, and thus for all of the body material pieces, a common piping is stitched. Thereafter, another pattern number is selected again and a piping having a length corresponding to the pattern number is sewn with all of the body material pieces, and, thus the above-described operation is repeated as many times as the types of the piping. In the second method each time one piping is sewn, the pattern number is reselected. In the case of the former, it is necessary to perform the removing from and mounting onto the fabric transfer mechanism of the fabric as many times as the number of the pipings. In both cases, there have been presented the disadvantages that operation is troublesome and the working efficiency of sewing cannot by improved.